This invention relates to a still camera system which is able to be selectably loaded with a film back or a still video back.
There has been disclosed an electronic still camera which takes a still image using a solid state image pickup device such as charge-coupled device (hereinafter referred to as CCD) and then records the still image in a magnetic disc. For example, at pages 80 to 85 of NIKEI ELECTRONICS issued on July 2, 1984, a Japanese Magazine has been introduced such a camera.
Also, Minolta Camera Kabushiki Kaisha, the asignee of the present invention, has filed a Japanese utility model application of 36821/1986 relating to a still camera able to selectably load a camera body with a still video back or a film back. This type of a still camera is constructed in such a manner that a still video back including a solid state image pickup device and an image processing circuit is removably attached to a usual camera body for carrying a film back. Also, the camera is constructed in such a manner that even when loaded with the still video back, the whole size does not become large and the appearance is nearly similar to a popular single-lens reflex camera. When loaded with the film back in place of the still video back, an image is formed on the film plane in the same manner as a usual single-lens reflex camera.
When a CCD of 2/3-inch measured diagonally is used as a solid state image pickup device of the still video back, the size of an effective image frame of the CCD equals about a quarter of that of the 35 mm film frame. Also, when a relay optical device provided in the still video back for reducing the image size of the 35 mm film to that of 2/3-inch CCD has a magnification of 1/2, the image size of the CCD equals a half of the actucal image size of the 35 mm film as understandable from the following calculation: 1/4/1/2=1/2 This is identical with a phenomenon which occurs when the focal length of an objective lens in use is made double. Accordingly, it will be apparent that when loaded with the still video back, undesirable results arise in means which is operated in accordance with the focal length information. The following means are operated in accordance with the focal length information: flashlight emission angle setting means, program line selection means for use in programmed automatic exposure control, means for selecting a reference value for warning camera shake, and shutter speed selection means for use in flashlight photography.
In such a still camera system, the program line selection, reference value for warning camera shake, shutter speed for flashlight photography and flashlight emission angle are set for the film back photography. Consequently, when loaded with the still video back, there arises a problem that the above-mentioned means fails to properly operate corresponding to actual photography condition.
Accordingly, an object of the present invention is to obviate the above-mentioned problems of the prior art.
Another object of the present invention is to provide a still camera system which is able to be loaded with a film back or a still video back selectably and able to provide focal length information corresponding to the frame size of still video back.
Further objects and advantages of the present invention will be apparent from the follwoing description of the invention